Isolating switch for a high-power electrical distribution system

ABSTRACT

The isolating switch employs semispherical-type electrode shielding energized parts which are mounted on the top of a pair of tilted insulator columns. The columns are mounted to a support frame by means of rotor bearings, which, when rotated by an appropriate mechanism, cause the tops of the insulator columns to move in a circular path. Linkages are employed and are responsive to column rotation in a first direction to electrically contact the blade and jaw of the switch arrangement, and to withdraw the blade and jaw in response to column rotation in a second direction to break contact. The smooth surfaces of the electrodes employed face one another in this second instance and provide an open gap condition which produces a substantially uniform electrostatic field between facing surfaces.

O United States Patent [1113524322 [72] Inventor Roy H. Albright FOREIGNPATENTS Greensburg. 395,843 7/1933 Great Britain 200/48 CB 1 p No 16,029936,456 11/1955 Germany 200/48 CB [22} Filed Mar. 3, 1970 [45] PatentedNov. 30 1971 Primary ExammerHerman J. Hohauser [73] Assignee ImperialCorporation A!mrney-Ostrolenk, Faber. Gerb & Soffen Pittsburgh, Pa.

ABSTRACT: The isolating switch employs semispherical-type [54] ISOLATINGSWITCH FOR A HIGILPOWER electrode shielding energized parts which aremounted on the ELECTRICAL DISTRIBUTION SYSTEM top of a pair of tiltedInsulator columns. The columns are 10 claimsa Drawing Figs. mounted to asupport frame by means of rotor bearings, which. when rotated by anappropriate mechanism, cause the U-S. tops of the in ulator olumn movein a circular path Link. Cl

31/00 ages are employed and are responsive to column rotation in a [50]Field Of Search ZOO/48, first direction electrically ontact the bladeand jaw of the 148,43 174/148, I44 switch arrangement, and to withdrawthe blade and jaw in response to column rotation in a second directionto break [56] References cued contact. The smooth surfaces of theelectrodes employed face UNITED STATES PATENTS one another in thissecond instance and provide an open gap Re.l9,588 5/l935 Baum ZOO/48 CBcondition which produces a substantially uniform electrostatic 2,084,8846/1937 Biermanns 200/148 field between facing surfaces.

ISOLATING SWITCH FOR A HIGH-POWER ELECTRICAL DISTRIBUTION SYSTEMBACKGROUND OF THE INVENTION This invention relates to electrical powertransmission and distribution systems, and, more particularly, to anovel insulating switch employed therein.

With the growth of the electrical power industry, transmission voltageshave increased from modest values of to l5 kv. to the present highlevels of 500 to 750 kv. As further growth in the industry occurs, it isanticipated that transmission voltages will extend to 1,000 to 1,500 kv.In the development towards these higher voltages, it has been recognizedthat a new concept in switch design is imperative due to the increasingnecessity to shield the energized switch parts at these higherpotentials.

It is an object of the present invention to provide a new and improvedisolating switch for use at such ultra-high voltages, which providesshielding for the contact members of the switch when the switch is inclosed position.

It is another object of the invention to provide such an isolatingswitch which enables the establishment of an open gap of limiteddimensions.

It is a further object of the invention to provide an isolating switchwhose overall length is kept reasonably small.

It is yet another object of the invention to provide such a switchwherein the contact members of the switch are also shielded when theswitch is in the open position.

It is also an object of the invention to provide an isolating switch foruse at ultra-high voltages wherein dielectric stress is kept reasonablysmall.

These and other objects of the invention will be more fully understoodfrom a consideration of the following description taken in connectionwith the drawings in which:

FIG. 1 shows a front elevational view of an isolating switch constructedin accordance with the invention;

FIG. 2 shows a plan view of the isolating switch of FIG. 1; and

FIG. 3 shows a perspective view illustrating the use of the isolatingswitch in a substation environment.

As will become clear hereinafter, it will be seen that such an isolatingswitch employs semispherical electrode shielding over the energizedparts of the switch These parts are mounted on the top of a pair oftilted insulator columns which are, in turn, mounted on rotor bearingsconnecting the insulator columns to a support frame. As the rotorbearings are controlled by appropriate means to open and close theswitch, the tops of the insulator columns are caused to move along acircular path. By means of linkages incorporated within the switch,circular movement in one direction causes engagement of the switch bladeand a cooperating jaw to connect one power line to another. This closedposition of the switch is to be contrasted with the open position,caused by circular movement in an opposite direction, whereby thelinkages serve to retract the blade and jaw into their respectiveelectrodes and to break the connection. At the same time, this lattermovement is such as to present the substantially smooth surfaces of theelectrodes employed towards one another to establish an open gapposition of a length substantially less than has heretofore beenexperienced with rod gap arrange ments in prior isolating switchdesigns. Such smooth gap conditions are more fully disclosed in pendingapplications Ser. No. 681,743, filed Nov. 9, 1967, and Ser. No. 839,456,filed July 7, 1969, both assigned to the same assignee as the instantapplication.

DESCRIPTION OF THE INVENTION As is well known, disconnecting switchesare designed to isolate electrical apparatus and portions of electricalsystems from energized lines for safe handling, maintenance, repair andinspection. It is, therefore, most important to provide adequateprotection for personnel working in the immediate region of thedisconnected equipment. Hence, when the switch is open, it is necessarythat the gap in the open position be adequate to withstand all usual, aswell as unusual, voltages which are impressed upon it by the system. Ifthe surge voltage causes the switch open gap to flash over, the lives ofpersonnel may be placed in serious jeopardy.

Such disconnecting switches are customarily designed so that the switchopen gap will withstand higher voltages than the insulator columns whichsupport the energized parts from the grounded metal base. As a result,flashover is much more likely to occur between the energized parts andground, rather than across the switch open gap. In this manner, theinsulator columns provide protection for the switch and operatingpersonnel against switching surge voltages and impulse voltages.However, this requires the provision of very large open gaps in theswitch to insure greater insulation strength or withstand than existsacross the insulator columns.

In the past, disconnecting switches have been constructed with largeopen gaps and having nonuniform electric field distribution due to thegeometry of the switch blade and associated contacts. In some instances,methods were provided to reduce the insulation strength of the insulatorcolumns to insure higher insulation strength across the open gap thanexisted down the insulator columns to earth. These methods have includedthe use of devices such as rod electrodes connected to the base of theinsulator columns. These methods, however, suffered from the drawbackthat the effective insulation strength or withstand of the insulatorcolumn cannot be reduced without limitation. Also present was theadditional drawback that the gap between the switch blades of thedisconnecting switches establishes the insulating distances asessentially that between rod electrodes, and since the withstand of theinsulator column must always be sufficiently high, this gap must ofnecessity remain large.

If these problems weren't enough in the present transmission systems of500 to 700 kv. the problems become more difficult to overcome in futuretransmission systems using voltages as high as l,00O-l ,500 kv. Thesesystems require disconnecting switches having insulator columns withsufficient voltage withstand. The insulator columns preferably should beof the order of 20 feet or so to provide adequate withstand forswitching surges of 2,300 kv., or more. Under these conditions, it willbe readily apparent that the switch open gap using existing switch bladearrangements must be considerably longer (e.g., 25-30 feet) to ensurethat flashover will be down the insulator column rather than across theopen gap.

As will now become clear, the present invention provides a new and novelisolating switch whereby the switch open gap is substantially shortenedto produce greater control of any flashovers without the necessity ofreducing the effective withstand of the insulator columns. Thisinvention also permits the use of shorter switch blades and a shortermounting base to effect a substantial saving; and, especially insituations where the withstand of the insulator column is not requiredto be high under operating conditions, these components may be shortenedeven further. The invention also permits a substantial savings in yardspace as a result of the use of shorter switch blades and shorter switchopen gaps. It has been found that a substantially uniform electrostaticfield is produced between the facing surfaces of the electrodes employedin this arrangement.

Referring now to FIGS. 1 and 2, there is shown a two insulatordisconnect switch assembly comprised of a supported switch base 10 whichis preferably of a rigid, metallic structure. The switch base 10 iselectrically grounded by a suitable conductor (not shown). The switchbase 10 is provided with rotor bearings 12 which secure the lowerportions of the insulator columns 14, 14a in any desireable manner suchthat the insulator columns can rotate with respect to base 10. As shownin the drawings, insulator columns 14, are tilted at an angle of some 30with respect to the base 10.

The opposite ends of the insulator columns 14, 14a

cooperate to support a pair of metallic electrodes and a retractableswitch blade. In particular, the insulator columns 14, 14a rigidlysupport a pair of spherical electrodes 16, 38, each of which is slottedalong the length thereof. A pair of switch blades or contact arms 20, 22are positioned to be extendable through the slots of electrodes 16, 18,respectively, when the switch is in the closed position. Switch blades20, 22 are each made of suitable conductive material so as to provide anefficient and continuous conductive path when connected in electricalcircuit.

Although not specifically shown as such for purposes of simplification,switch blade has a projecting beavertail at its contact end tocooperatively engage with the contacts 26 and 28 of the jaw 30 of theswitch blade 22. Conductors 32 and 34 are respectively coupled to switchblade elements 20 and 22 in this and other environments, in any suitablemanner, and connect these components to suitable utilization apparatus(not shown). It is to be noted that while spherical electrodes have beenshown, the electrodes 16 and 18 may also be generally shaped toroidalrings, ellipsoids or spheroids. ln the arrangement of FIGS. 1 and 2, theslotting of the electrodes 16, 18 effectively provide a semisphericalshielding over the energized parts 20, 22.

The retractable blades 20 and 22 for alternately closing and opening thedisconnect switch are shown as being in alignment in the plane formed bythe openings in the two spherical electrodes 16, 18. These blades areoperated to slide within the opening and to make electrical contactbetween them when the switch is desired to be closed. When the switch isto be opened, the blades 20 and 22 are arranged to wholly retract withintheir respective electrodes. Such opening and closing action is governedby pairs of castings 36, 36a, shafts 38, 38a and linkages 40, 40a, withone of each pair being associated with electrodes 16 and 18,respectively.

As will be seen from the drawings, casting 36 couples the top of theinsulator column 14 to the electrode 16 and casting 36a couples the topof insulator column 140 to the electrode 18. Each casting is shown toproject in a direction towards the center of rotation of the rotorbearing 12. Shaft 38 is attached to the end of casting 36 at a point inalignment with the center of rotation of the left hand rotor bearing 12,and is employed to support the conductor 32. Shaft 38a, similarly, is.attached to the end of casting 360 at a point in alignment with thecenter of rotation of the right-hand rotor bearing 12, and supports theconductor 34. Since the shafts 38 and 38a effectively are in coaxialalignment with the rotor bearings l2, they will rotate in a mannersimilar to that of the rotor bearings. Also, it will be noted that nohorizontal movement of the shafts 38 and 380 will take place, so thatthe ends of conductors 32 and 34 will remain in a substantiallyhorizontal position. As will be appreciated, rotation of the bearings 12can be effected by a conventional gear device (100 in FIG. 3), such as amotorized gear box supported by the switch base 10.

The previous description has been with the understanding that the rotorbearings 12 have been moved to position the spherical electrodes 16 and18 in the position shown in FIG. 1 and in solid lines in FIG. 2. Thisbasically represents the closed position of the disconnect switch, witha complete electrical circuit path being established between conductors32 and 34. The following description is directed towards the retractionof the switch blades 20, 22 within their respective spherical electrodes16, 18 to open the switch connection.

As will be evident to one skilled in the art, movement of the rotorbearings 12 serves to rotate the upper ends of insulator columns 14, 14ain a circular pattern. Because of the connections between insulatorcolumns 14, 14a and castings 36, 36a, this movement of the rotorbearings 12 also effects circular movement of the spherical electrodes16, 18 in a horizontal plane. Since the center of rotation of the rotorbearings is in alignment with shaft 38, on the one hand, and with shaft380, on the other hand, the circular movement will be about theseshafts. This rotation is illustrated by the dotted configuration of theelectrodes 16', 18' in FIG. 2.

By virtue of the linkage arrangements 40 and 40a joining a pin on thecasting 36 and 36a to respective switch blades 20,

22, the circular rotation of the rotor bearing 12 not only serves tomove the electrodes 16 and 18 in a circular path, but also serves toretract the switch blades 20 and 22 wholly within the electrodes when inthe positions shown by representations 16, 18'. In this open position ofthe switch, only the substantially smooth surfaces of the sphericalelectrodes 16', 18' face one another, to provide open gap region. Asdescribed in the aforementioned pending applications Ser. No. 68l,743and Ser. No. 839,456, such an open gap between substantially smoothsurfaces can be much less than open gap distances between rodelectrodes, while continuing to insure that any flashover will be downthe insulator column instead of across the open gap. in this manner, itwill be seen that the use of the spherical electrodes permits an opengap of limited dimensions and, therefore, enables the overall lengths ofthe disconnect switch to be kept small, even for the ultra-high highvoltage environments transmitting lOOO to 1500 kv. voltages.

Other advantages are present with the disconnect switch describedherein. Thus, it will be seen that the spherical electrodes 16, 18provide shielding for the retractable switch blades 20, 22 both when theswitch is closed and when the switch is in the open position. Safety isthus maintained throughout the usage of the switch in transmittingelectrical power and when disconnecting the switch to provide themaintenance and repair function. It will also be noted that indentations (such as 42, 420) can be provided in the lower portions of thespherical electrodes 16, 18, to shield the upper portions of theinsulator columns 14, 14a so as to reduce dielectric stress. This latterfeature is easily attainable with the present design, and is muchsimpler than characterized by prior switch arrangements where properdielectric requirements were had only by increasing switch dimensions asvoltages increased.

A perspective view illustrating the relative dimensions of the componentparts of the isolating switch mechanism as it might be used in a threephase substation environment is shown in FIG. 3.

While there has been described what is considered to be a preferredembodiment of the present invention, it will be appreciated that furthermodifications are feasible, not only through the use of employingtoroidal rings, ellipsoids or spheroids as described above. Othersimilar arrangements are well within the scope of the present invention,and fall within the scope of the claims as defined below.

lclaim:

1. An electric switch comprising:

first and second spaced apart hollow electrodes operative to produce asubstantially uniform electrostatic field between facing surfacesthereof when in a disengaged switch position, with each such electrodehaving a longitudinally aligned slotted portion;

first and second retractable switch blades respectively mounted withinsaid electrodes;

first and second means operative to respectively rotate said first andsecond electrodes in a first direction to align the slotted portionsthereof when switch engagement is desired and to rotate said electrodesand said slotted portions in a second direction away from one anotherwhen switch disengagement is desired;

mechanical linkage means each cooperating with an associated one of saidelectrodes and respectively coupled to one of said first and secondmeans to move said first and second switch blades along linear paths soas to protrude through said slotted portions to make electrical contacttherebetween when said electrodes rotate to the engaged switch positionand to retract said switch blades within said slotted portions and alongsaid linear paths as said switch blades rotate in paths transverse tosaid linear paths to break said electrical contact when in said disengaged switch position;

first and second conductors having terminals extending into saidelectrodes for coupling said switch into an electrical circuit;

first and second pivot connections respectively positioned within saidfirst and second electrodes for coupling their associated switch bladeto one of said conductors;

said first and second means each being coupled to said mechanicallinkages and said electrodes at a point spaced from its associated pivotconnection for rotating said electrodes about their respective pivotconnections.

2. An electric switch as defined in claim 1 wherein said first andsecond electrodes comprise a pair of spherical shaped hol low electrodesoperative to produce a substantially uniform electrostatic fieldtherebetween when in a disengaged switch position to thereby shield boththe terminals and the switchblades.

3. An electric switch as defined in claim I wherein said first andsecond electrodes comprise a pair of spherical electrodes mounted onfirst and second insulator columns, respectively, and wherein saidinsulator columns are supported by an electrically grounded base.

4. An electric switch as defined in claim 3 wherein said first andsecond means includes said first and second insulator columns and amechanism for simultaneously rotating said columns such that themounting of said columns to said electrodes is operative to produce arotation of said electrodes in a horizontal plane in a circular path inresponse to excitation of said mechanism.

5. An electric switch as defined in claim 4 wherein said mechanicallinkage means includes a linkage system coupled between said firstmember of each electrode-insulator column arrangement and its associatedretractable switch blade for projecting and retracting said switch bladewithin its respective electrode under excitation of said mechanism.

6. An electric switch as defined in claim 5 wherein said insulatorcolumns are each oriented in a vertical plane with respect to thegrounded electrical base, but tilted towards the horizontal from anupright vertical position 7 An electric switch as defined in claim 6wherein the undersides of said spherical electrode are indented toreduce dielectric stress.

8. An electric switch as defined in claim 6 wherein said firstretractable switch blade includes a projecting beavertail at its contactend and said second retractable switch blade has a jaw contact at itscorresponding end to cooperatively move into sidewise engagement withsaid first switch blade in the engaged switch position.

9. A switch comprising:

a support;

first and second diagonally aligned insulators;

first and second means for rotatably mounting the lower ends of saidinsulators upon said support;

a pair of hollow slotted metallic shells;

a pair of conductors each having end terminals extending into theinteriors of said shells;

first and second slidably engageable switch blades each positionedwithin an associated shell;

first and second pivot connections respectively coupling each endterminal to an associated one of said switchblades;

first and second arms positioned within said shells and secured to theupper ends of said insulators and to the undersides of their respectiveshells at points removed from said pivot connections for rotating saidshells about respective imaginary lines extending between a pivotconnection and an associated one of said first and second means.

10. The switch of claim 9 further comprising:

first and second mechanical linkages each coupled between one of saidfirst and second arms and its associated switchblade for linearly movingtheir switch blades out of said shells and into engagement when saidswitch is in the closed position and for withdrawing their associatedswitchblades into their associated shells when said switch is in theopen position whereby said shields provide dielectric shielding fortheir associated switchblades and conductor terminals.

t I? t

1. An electric switch comprising: first and second spaced apart hollowelectrodes operative to produce a substantially uniform electrostaticfield between facing surfaces thereof when in a disengaged switchposition, with each such electrode having a longitudinally alignedslotted portion; first and second retractable switch blades respectivelymounted within said electrodes; first and second means operative torespectively rotate said first and second electrodes in a firstdirection to align the slotted portions thereof when switch engagementis desired and to rotate said electrodes and said slotted portions in asecond direction away from one another when switch disengagement isdesired; mechanical linkage means each cooperating with an associatedone of said electrodes and respectively coupled to one of said first andsecond means to move said first and second switch blades along linearpaths so as to protrude through said slotted portions to make electricalcontact therebetween when said electrodes rotate to the engaged switchposition and to retract said switch blades within said slotted portionsand along said linear paths as said switch blades rotate in pathstransverse to said linear paths to break said electrical contact when insaid disengaged switch position; first and second conductors havingterminals extending into said electrodes for coupling said switch intoan electrical circuit; first and second pivot connections respectivelypositioned within said first and second electrodes for coupling theirassociated switch blade to one of said conductors; said first and secondmeans each being coupled to said mechanical linkages and said electrodesat a point spaced from its associated pivot connection for rotating saidelectrodes about their respective pivot connections.
 2. An electricswitch as defined in claim 1 wherein said first and second electrodescomprise a pair of spherical shaped hollow electrodes operative toproduce a substantially uniform electrostatic field therebetween when ina disengaged switch position to thereby shield both the terminals andthe switchblades.
 3. An electric switch as defined in claim 1 whereinsaid first and second electrodes comprise a pair of spherical electrodesmounted on first and second insulator columns, respectively, and whereinsaid insulator columns are supported by an electrically grounded base.4. An electric switch as defined in claim 3 wherein said first andsecond means includes said first and second insulator columns and amechanism for simultaneously rotating said columns such that themounting of said columns to said electrodes is operative to produce arotation of said electrodes in a horizontal plane in a circular path inresponse to excitation of said mechanism.
 5. An electric switch asdefined in claim 4 wherein said mechanical linkage means includes alinkage system coupled between said first member of eachelectrode-insulator column arrangement and its associated retractableswitch blade for projecting and retracting said switch blade within itsrespective electrode under excitation of said mechanism.
 6. An electricswitch as defined in claim 5 wherein said insulator columns are eachoriented in a vertical plane with respect to the grounded electricalBase, but tilted towards the horizontal from an upright verticalposition.
 7. An electric switch as defined in claim 6 wherein theundersides of said spherical electrode are indented to reduce dielectricstress.
 8. An electric switch as defined in claim 6 wherein said firstretractable switch blade includes a projecting beavertail at its contactend and said second retractable switch blade has a jaw contact at itscorresponding end to cooperatively move into sidewise engagement withsaid first switch blade in the engaged switch position.
 9. A switchcomprising: a support; first and second diagonally aligned insulators;first and second means for rotatably mounting the lower ends of saidinsulators upon said support; a pair of hollow slotted metallic shells;a pair of conductors each having end terminals extending into theinteriors of said shells; first and second slidably engageable switchblades each positioned within an associated shell; first and secondpivot connections respectively coupling each end terminal to anassociated one of said switchblades; first and second arms positionedwithin said shells and secured to the upper ends of said insulators andto the undersides of their respective shells at points removed from saidpivot connections for rotating said shells about respective imaginarylines extending between a pivot connection and an associated one of saidfirst and second means.
 10. The switch of claim 9 further comprising:first and second mechanical linkages each coupled between one of saidfirst and second arms and its associated switchblade for linearly movingtheir switch blades out of said shells and into engagement when saidswitch is in the closed position and for withdrawing their associatedswitchblades into their associated shells when said switch is in theopen position whereby said shields provide dielectric shielding fortheir associated switchblades and conductor terminals.